This invention relates to a plastic fastener comprising a female member formed of a flange, a leg extended downwardly from the lower side of the flange and adapted to permit increase in the outside diameter of its barrel portion and an insertion hole bored along the axis of the leg downwardly from the upper surface of the flange, and a male member formed of a head portion and a shaft portion extended downwardly from the lower side of the head portion and adapted to be forcibly driven into the insertion hole of the female member. More particularly, this invention relates to a plastic fastener of the type comprising a female member and a male member as described above, which plastic fastener is improved so that after it has joined two panels face to face with the shaft portion of the male member forcibly driven into the insertion hole of the female member, it permits extraction of the tightly inserted shaft portion required for the purpose of separating the panels from their tight union to be readily accomplished.
The fastener described above which comprises the female and male members is used as for uniting two panels face to face or fastening to a panel a metal piece fitted on a part, for example. Use of this fastener is generally effected, as when a plurality of panels are required to be united in a stratified manner, for example, by inserting the leg of the female member through perforations formed at exactly corresponding positions through the individual panels until the flange collides with one outermost panel surface, then forcibly driving the shaft portion of the male member into the insertion hole of the female member thereby radially expanding the portion of the leg protruding from the perforations, causing the panels to be squeezed between the radially expanded portion of the leg and the flange and tightly united with one another. In this case, it is a general practice that the shaft portion of the male member is forcibly driven into the insertion hole of the female member until it is completely buried therein, namely, until the head portion collides with the upper surface of the flange, so that it will not easily come off the insertion hole. Once the union of panels by this fastener is completed, therefore, this union is not broken by ordinary vibrations, impulses and other similar external forces. There are, however, cases where this union must be broken for some reason or other.